Decks and fences are among the most frequently attempted DIY projects and among the most frequently built without checking. Both have real requirements, and both have consequences when ignored.
Fences
Most Washington jurisdictions set a height below which a residential fence requires no permit, with taller fences requiring one. The specific height varies locally.
What catches people out is not usually the permit but the other constraints. Corner lots frequently have sight-line requirements limiting height near intersections. Front yard fences are often held to a lower limit than rear ones. Properties near shorelines, wetlands or steep slopes may fall within critical area designations affecting what can be built.
Then there is the boundary itself. A fence built in the wrong place is a genuinely expensive mistake to unwind, and assumptions about where a line runs are frequently wrong. For anything substantial, knowing the boundary properly beforehand is worth the effort.
Decks
Decks are more consistently permit-relevant, because they carry people at height and, where attached, transfer load into the house.
The common triggers are height above grade beyond a specified threshold, and attachment to the structure. A ground-level platform may fall below the threshold; anything raised, and anything attached, generally does not.
Attachment is the important one. A deck ledger fastened incorrectly to the house is a genuine structural failure risk, and deck collapses overwhelmingly involve the ledger connection. This is the single strongest argument for permitted, inspected deck construction.
The Eastern Washington difference
This is where generic guidance causes real problems. Snow load and frost depth requirements in Spokane, Yakima and the Tri-Cities are substantially different from the Puget Sound lowlands.
A deck design adequate in Seattle may be under-specified in Spokane, both structurally and in footing depth. Frost heave lifts inadequately founded posts over successive winters, and snow load on a deck is a real design input rather than a theoretical one.
Online plans and kits typically assume milder conditions. If you are east of the Cascades, confirm the design is specified for your actual snow load and frost depth rather than assuming a general plan applies.
Materials and Washington’s climate
West of the Cascades, persistent damp means rot resistance and drainage detailing matter more than they would elsewhere — how water leaves the deck, whether the ledger flashing keeps it out of the wall, and whether the substructure can dry.
East of the Cascades, UV degradation and freeze-thaw cycling dominate. Different problem, different material priorities.
Before you start
Confirm the permit threshold for your jurisdiction and project. For a deck, establish whether it will be attached and how high it sits. East of the Cascades, confirm snow load and frost depth. For a fence, confirm height limits, sight-line rules and — genuinely — where your boundary is.